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Extending storage capacity

JenniferJennifer
in General
Hi,

At present, only 500,000 data entires may be stored within the internal memory (approx 1 hour). Is there any way this could be increased to allow for data readings longer than an hour's worth?

Also, is there a way to transfer data via a wire after logging data to avoid the long download time?

Thanks!

Comments

  • EricEric
    edited October 2017
    Outside of hardware changes, you can either 1) reduce the sampling frequency or 2) right shift the data by 1 byte to compact the data.  

    No, the boards presently available only allow power through USB.  Enabling data transfer through the USB port is something we would like to have in future designs.  If the download times are too long, perhaps streaming might be the better option.
  • user295145user295145
    Is the documentation here out of date, where it says there is room for around 14,000 entries? Is it now 500,000?

    Thanks
  • EricEric
    edited February 2018
    For the new boards, it is ~500,000 IMU entries.
  • CoreyPewCoreyPew

    Hello,

    I wanted to see if this was something that had been updated recently. I would like to do an activity tracking project and it would be much easier to log all the data directly to an SD card rather than be required to carry a phone at all times to record data. Is there any way to push data through the USB port or possibly add an SD card reader in some other way to record data? Thanks!

  • EricEric

    The point of logging is the ability to record data without being connected to the host device. Bringing a mobile device with you defeats the purpose of logging, and that point, you might as well stream the data instead.

    No, there are no plans to add SD card support. Data transfer through USB is a nice to have feature it would take a lower priority to Bluetooth 5.0 support.

  • CoreyPewCoreyPew

    Is it possible to hook up an SD card reader as a peripheral via the SPI interface and log data that way?

  • EricEric

    On paper, I suppose it could work though I have no idea if it actually will work.

    Is the 8MB flash chip not big enough for your use case? What exactly are your recording that would warrant SD card / USB data transfer support?

  • CoreyPewCoreyPew

    I would like to record activity at 50-100 Hz throughout the day. At 50Hz, the 500,000 data entries provided by the 8 MB memory would give me less than 3 hours of data. I need to be able to record a few weeks or up to a month of data. Although data streaming or storing on the user's phone would be optimal, if I require participants to own a smartphone it will limit my recruiting potential and I don't want to have to supply them with a smart device if I can avoid it. If I can add an SD card I could potentially record over 7 days per GB at 100 Hz. I am still working out the protocol on my project and want to have the option to do long-term recording should the need arise.

  • CoreyPewCoreyPew

    Eric,

    I am relatively new to working with these types of devices. Do you have any thoughts on how best to implement the addition of an SD card expansion? Is there any way to directly access the SPI bus from the internal module pins and hardwire an SD card or is data communication only available through the Bluetooth interface? Thanks!

  • EricEric

    Well, you should first see if you can successfully write any data to the sdcard with the existing SPI api.

    Any of the GPIO pins can be used for the required SPI signals (miso, mosi, clock, ss). When you use the read/write data over the SPI bus, use those pin numbers for their respective paramenters.

    To actually send write / read commands, you will need to program the MetaMotion board to do those operations through the BLE link.

  • CoreyPewCoreyPew

    Eric,
    Thank you I will give this a try!

This discussion has been closed.